1. Field of the Invention
The present invention relates to a sheet processing apparatus that binds sheets delivered from an image forming apparatus such as a copier or a printer, and to the image forming apparatus including the sheet processing apparatus.
2. Description of the Related Art
As a related art of the present invention, a sheet processing apparatus (hereinafter, also referred to as “processing apparatus”) is known, which binds sheets subjected to image formation in an image forming apparatus. The processing apparatus includes: a processing tray that accumulates thereon the sheets to be bound; a binding device (stapler) that binds a sheet bundle on the processing tray; and a storing tray to which the sheet bundle bound on the processing tray is delivered.
In a type of the processing apparatus, there are provided a mode of binding end portions on one end side of the sheets, and a mode of binding end portions on another end side of the sheets (refer to Japanese Patent Application Laid-Open No. 2005-132635). In this apparatus, on the processing tray, tip ends of the sheets are aligned by being thrust against a stopper (reference fence), the stopper is retreated by being rotationally moved downward after the tip ends are aligned, and the binding device is moved to designated binding end portions along aligned edge portions of the sheets.
As transport means for moving, to a binding position, the sheet bundle accumulated on the processing tray, a transport method is known, in which one side of a sheet bundle is gripped by a gripping device, and this gripping device is moved, to thereby transport the sheet bundle (refer to Japanese Patent Application Laid-Open No. 02-89772). This grip/transport method is excellent in that a deviation amount of the sheet bundle is small as compared with a method in which the sheet bundle is transported to the binding position by being pushed by a pushing member. Further, a transport method is known, in which one side of the sheet bundle is gripped by a gripping device, and this gripping device is moved, to thereby transport the sheet bundle to a storing tray (refer to Japanese Patent Application Laid-Open No. 2005-132609).